Influence of Water Uptake, Charge, Manning Parameter,and Contact Angle on Water and Salt Transport in Commercial Ion ExchangeMembranes

In electrochemical processes such as electrodialysis or redox flow batteries, where ion exchange membranes (IEMs) play a critical role in process performance, energy losses can be reduced by minimizing the permeability of IEMs to water and salt. In pure, homogeneous polymer membranes, water permeability is known to be controlled by the size of the free volume elements. However, there is very limited evidence concerning the extent to which this theory applies to practical, commercial IEMs, which frequently have more complex structures. We recently reported water and salt transport characteristics (i.e., permeability, partition, and diffusion coefficients) of 20 commercial IEMs, and demonstrated that water and salt transport were governed primarily by the microstructure of the membrane rather than the polymer chemistry. To further investigate the factors that determine water and salt transport in commercial IEMs, in this study we adopted a statistical approach informed by free volume theory and other litera...